Sunday, July 3, 2016

Oh, patents! A. T. Cross crayon holders

Copyright © Françoise Herrmann

In US 296539 A.T. Cross discloses one of his crayon (or lead) holder inventions, and by the same token, some important steps in the birth of what are now called mechanical pencils.

The problematic situation addressed in the Cross lead or crayon holder patents concerns the mechanically-driven ejection of unused crayon (or lead) stubs. In other words, once most of the lead has been used and screwed down through the tube bore, and there is just a stub left, located inside or flush with the outer edge of the crayon tube, how do you remove it from the plunger jaws of the lead carrier, without having to reverse, steps, retracting (or screwing) the stub back up to the top, and removing it manually through the top of the pencil?

The mechanically-driven solution that Cross provided is a spring soldered to a forcer (called a “plunger” elsewhere, and corresponding to that part of the lead carrier which pushes the lead as it is being gradually used and screwed down through the pencil barrel). 

The spring is soldered to the bottom of the forcer to prevent it from "escaping", and it is actuated by a clever pin, slot and spur design, triggered as the user screws the lead down --just that one notch further.  

The spring forcer pin further includes a cam function that forces the lead holder jaws to open laterally, thereby immediately releasing the lead stub, which the spring in turn also propels further down the barrel, so that it may be removed through the lower part of the pencil holder.  

Thus, it is only for re-inserting a new lead, that the movement of the screw will have to be reversed so as to bring the lead carrier back up to the top of crayon holder. 

Below, the figure drawings 1-6, extracted from US296539, are included.

For comprehension and translation purposes, you will definitely want to initially key the illustrations --just as A.T. Cross does in his handwritten Canadian patents (e.g. CA10451, CA10682, CA17448, although not for the same reasons... 

It is otherwise helpful to know, per the patent specifications,  that all the lettering is consistent from one illustration to another. I have included such a key for the US296539 illustrations (1-6), which was directly layered onto to the extracted illustrations.  

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